The present invention relates to a drive device for a circuit breaker with a ratchet wheel for cocking an energy accumulator by stepwise rotation of the ratchet wheel by means of a transporting ratchet, as well as with a device for lifting the transporting ratchet out of the teeth of the ratchet wheel when the latter rotates in the course of releasing the tension of the energy accumulator.
A drive device of this type has become known from U.S. Pat. No. 4,167,988. The device for lifting the transporting ratchet there has the purpose of preventing damage which can occur during the very rapid rotation of the ratchet wheel connected with the tension release of the energy accumulator at its teeth as well as at the transporting ratchet. Damage of this kind limits the useful life of the drive device and must therefore be kept so low that the number of switching cycles provided in practice can be executed.
The use of a separate device for lifting the transporting ratchet is based on the insight that also an intentional overdesign of the interacting parts is not sufficient to prevent the detrimental wear. The reason for this is seen in the extremely high velocity of rotation of the ratchet wheel during the tension release of the energy accumulator and a correspondingly high velocity when the teeth of the ratchet wheel and the transporting ratchet meet. In detail, this operation begins when the transporting ratchet is flung away against its contact pressure. The transporting ratchet then tilts about its pivot and strikes a stop which reflects the transporting ratchet. The latter then hits the ratchet wheel again and is flung off. In the mentioned known device for preventing wear of the drive device, the first flinging-off of the transporting ratchet away from the ratchet wheel is utilized for releasing a latch which is under spring tension and holds the transporting ratchet in the lifted condition. However, it is then necessary to reset the latch before the energy accumulator is cocked again, so that the transporting ratchet can again get into engagement with the teeth of the ratchet wheel.